The present invention generally relates to industrial control systems and in particular to an automation interface for industrial controllers.
Industrial controllers are special purpose computers used for controlling factory automation devices. Under the direction of a stored program, a processor of the industrial controller examines a series of inputs reflecting the status of a controlled process or device and changes outputs affecting control of the controlled process or device. Generally industrial controllers are constructed in modular fashion to accommodate different application requiring different numbers and types of input/output (I/O) circuits as is determined by the particular device or process being controlled. The stored control program runs in real-time to provide outputs to the controlled process as electrical signals to outputs such as actuators and the like. The outputs are based on the logic of the control program and inputs received from sensors of the controlled process.
The industrial controller or programmed logic controller (PLC) executes a series of operations that are performed sequentially and repeatedly. In general, the series of operations includes an input scan, a program scan and an output scan. During the input scan the PLC examines the on or off state of the external inputs and saves these states temporarily in memory (e.g., a file). During the program scan the PLC scans the instruction of the program and uses the input status to determine if an output will be energized. The output results are then saved to memory (e.g., a file). During the output scan the controller will energize or de-energize the outputs based on the output results stored in memory to control the external devices.
A conventional language for programming the stored program is relay ladder logic. Each ladder logic program comprises one or more ladder logic statements, referred to as rungs or instructions. The ladder logic statements define relationships between an output variable and one or more input variables. Input variables are variables that correspond to signals at input terminals and output variables are variables that correspond to signals at output terminals. In relay ladder logic, the input and output signals may be represented graphically as contact symbols and coil symbols arranged in a series of rungs spanning a pair of vertical power rails. A typical ladder logic statement may indicate that a specific output variable is xe2x80x9conxe2x80x9d if and only if a first and a second input is xe2x80x9conxe2x80x9d. The ladder logic program not only manipulates single-bit input and output data representing the state of the sensing and operating devices, but also performs arithmetic operations, timing and counting functions and more complex processing operations.
A ladder program can be created by connecting a special input module to a PLC that includes a small keyboard and entering ladder logic statements directly into the memory of the PLC. Another method of creating a ladder logic program involves, utilizing a ladder logic program development/editor tool residing on a separate device, such as a personal computer. An operator or programmer of the personal computer draws a series of ladder logic graphs representing each rung or instruction directly on the computer display screen. Once the ladder logic program is complete, the PC software converts the graphs into the corresponding ladder logic commands. The ladder logic command are then transferred to the PLC and stored in the PLC memory.
A PLC and/or a personal computer device can store one or more ladder logic programs and versions. However, a user must manually upload, download, edit and develop ladder logic programs at a work station or personal computer running a developer/editor application program. Furthermore, data backup and storage must be manually invoked by an operator through the application program or be conducted through another system separate from the application program. Accordingly there is an unmet need in the art to provide an improved system and method for developing, editing, replacing and monitoring industrial control programs and/or data associated with a controlled process involving the industrial controller.
The following presents a simplified summary of the invention in order to provide a basic understanding of some aspects of the invention. This summary is not an extensive overview of the invention. It is intended to neither identify key or critical elements of the invention nor delineate the scope of the invention. Its sole purpose is to present some concepts of the invention in a simplified form as a prelude to the more detailed description that is presented later.
The present invention provides a system and method for providing an automation interface for interacting with industrial controllers. The automation interface provides for programming, editing, monitoring and maintenance of industrial controllers programmatically from a local or remote location. The automation interface component is adapted to communicate with industrial controllers by integrating a computer process interface library into the automation interface component. The computer process interface library exposes the automation interface component to client application processes, so that the client application processes can communicate with the at least one industrial controller programmatically. The automation interface is provided with functionality for downloading, uploading and programming of control programs to the processors of the industrial controllers.
The automation interface also allows for data associated with one or more control processes to be accessible programmatically. The data can be used to determine status information of the one or more control processes or logged for later analysis. The automation interface can be exposed to a web service, such that industrial controllers can be accessed via the Internet. Data associated with one or more control processes can be logged at a third party data store, so that system backup can be outsourced.
The following description and the annexed drawings set forth in detail certain illustrative aspects of the invention. These aspects are indicative, however, of but a few of the various ways in which the principles of the invention may be employed. Other advantages and novel features of the invention will become apparent from the following detailed description of the invention when considered in conjunction with the drawings.